On 2015-03-31 22:01, Andrei Alexandrescu wrote:
I made a few editorial passes, no major changes. I think there's still a
fly in the ointment. The resolution algorithm goes:
1. If xyz is a symbol (member, method, enum etc) defined inside
typeof(obj) then lookup is done.
2. Otherwise, if xyz is a symbol introduced in the base class (where
applicable), then lookup is done.
3. Otherwise, if opDispatch!"xyz" exists, then lookup is done.
4. Otherwise, alias this is attempted transitively, and if xyz is found,
then lookup is done.
5. Otherwise an UFCS rewrite is effected.
This puts opDispatch in between inheritance and subtyping, which I think
we discussed is inappropriate - alias this should be effectively subtyping.
If we're really convinced alias this means multiple subtyping, the
inherited type should not have a special role. However, it simplifies a
lot of things to give one particular subtype a leg up on all others. So
I think this would work:
1. If xyz is a symbol (member, method, enum etc) defined inside
typeof(obj) then lookup is done.
2. Otherwise, if xyz is a symbol introduced in the base class (where
applicable), then lookup is done.
3. Otherwise, if xyz is found at least via either an opDispatch!"xyz" or
alias this conversion, then lookup is done.
4. Otherwise an UFCS rewrite is effected.
Should opDispatch or "alias this" ever be looked up in the base class?
--
/Jacob Carlborg
